Current integrated circuit (IC) chip packaging technologies commonly rely on either a lead frame, interposer or miniature interconnection substrate to serve as an interconnection base for redistributing the I/O (input/output terminals) of the IC to a more practical and useful lead spacing or pitch between I/O terminals for next level assembly. Interconnection between the IC or die is normally accomplished using either wire bonding or flip chip technology. The I/O terminals on the finished IC package are located either on the sides of or beneath the chip, however in some special cases, such as for stacking memory ICs to increase memory density, the terminals may be provided with a common land that can be accessed from both top and bottom. The lead frames, interposers and miniature interconnection substrates that provide the I/O pitch translation, obviously have associated with them both materials and manufacturing cost.
Moreover, for some types of I/O pitch translation devices, such as miniature interconnection substrates there is an associated cost for testing to assure that all connections are complete and that there are no electrical shorts.
Because each IC chip design is unique, the interconnection substrate used in manufacture of the final package is often also unique to the chip and requires the creation of a package design with each interconnection requiring its own circuit path on the substrate. This is especially true for higher I/O count ICs. Thus time, materials and processes used to create IC packages while providing benefit also add to cost and delay in terms of manufacturing lead time which can limit opportunity associated with getting a product to market early. Of course in the best case, any interconnection would be made directly to the IC termination land and this can be and often is the case for chips having few I/O terminations. However, as I/O counts rise, this becomes a problem, thus a circuit substrate is commonly used to redistribute the I/O and the terminations to the chip are made locally. In addition because of the limits of current manufacturing practices, the same interconnection materials and process steps which add cost to the overall structure also typically limit both its performance and abrogate its versatility. Performance limits are due to the electrical parasitics associated with the changes in circuit materials, transitions through and around electrical features such as vias the like which in turn limit the design versatility. As a result of these limitations of current IC package design and manufacturing practices thus leave room and opportunity for improvements.